kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-24 19:10:26 +00:00
Code Issues Releases Packages Activity
No description
1,221,973 commits 117 branches 5,803 tags 5.7 GiB
  • C 96.8%
  • Assembly 0.9%
  • Rust 0.7%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Yonghong Song e36373dc5e bpf: Mark bpf_spin_{lock,unlock}() helpers with notrace correctly 
[ Upstream commit 178c54666f ]

Currently tracing is supposed not to allow for bpf_spin_{lock,unlock}()
helper calls. This is to prevent deadlock for the following cases:
  - there is a prog (prog-A) calling bpf_spin_{lock,unlock}().
  - there is a tracing program (prog-B), e.g., fentry, attached
    to bpf_spin_lock() and/or bpf_spin_unlock().
  - prog-B calls bpf_spin_{lock,unlock}().
For such a case, when prog-A calls bpf_spin_{lock,unlock}(),
a deadlock will happen.

The related source codes are below in kernel/bpf/helpers.c:
  notrace BPF_CALL_1(bpf_spin_lock, struct bpf_spin_lock *, lock)
  notrace BPF_CALL_1(bpf_spin_unlock, struct bpf_spin_lock *, lock)
notrace is supposed to prevent fentry prog from attaching to
bpf_spin_{lock,unlock}().

But actually this is not the case and fentry prog can successfully
attached to bpf_spin_lock(). Siddharth Chintamaneni reported
the issue in [1]. The following is the macro definition for
above BPF_CALL_1:
  #define BPF_CALL_x(x, name, ...)                                               \
        static __always_inline                                                 \
        u64 ____##name(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__));   \
        typedef u64 (*btf_##name)(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__)); \
        u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__));         \
        u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__))          \
        {                                                                      \
                return ((btf_##name)____##name)(__BPF_MAP(x,__BPF_CAST,__BPF_N,__VA_ARGS__));\
        }                                                                      \
        static __always_inline                                                 \
        u64 ____##name(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__))

  #define BPF_CALL_1(name, ...)   BPF_CALL_x(1, name, __VA_ARGS__)

The notrace attribute is actually applied to the static always_inline function
____bpf_spin_{lock,unlock}(). The actual callback function
bpf_spin_{lock,unlock}() is not marked with notrace, hence
allowing fentry prog to attach to two helpers, and this
may cause the above mentioned deadlock. Siddharth Chintamaneni
actually has a reproducer in [2].

To fix the issue, a new macro NOTRACE_BPF_CALL_1 is introduced which
will add notrace attribute to the original function instead of
the hidden always_inline function and this fixed the problem.

  [1] https://lore.kernel.org/bpf/CAE5sdEigPnoGrzN8WU7Tx-h-iFuMZgW06qp0KHWtpvoXxf1OAQ@mail.gmail.com/
  [2] https://lore.kernel.org/bpf/CAE5sdEg6yUc_Jz50AnUXEEUh6O73yQ1Z6NV2srJnef0ZrQkZew@mail.gmail.com/

Fixes: d83525ca62 ("bpf: introduce bpf_spin_lock")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20240207070102.335167-1-yonghong.song@linux.dev
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-03-26 18:19:29 -04:00
arch arm64: dts: mediatek: mt7622: add missing "device_type" to memory nodes 2024-03-26 18:19:29 -04:00
block block: sed-opal: handle empty atoms when parsing response 2024-03-26 18:19:12 -04:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: algif_hash - Remove bogus SGL free on zero-length error path 2024-02-23 09:25:11 +01:00
Documentation ovl: add support for appending lowerdirs one by one 2024-03-26 18:19:18 -04:00
drivers wifi: iwlwifi: mvm: Fix the listener MAC filter flags 2024-03-26 18:19:29 -04:00
fs ovl: Always reject mounting over case-insensitive directories 2024-03-26 18:19:18 -04:00
include bpf: Mark bpf_spin_{lock,unlock}() helpers with notrace correctly 2024-03-26 18:19:29 -04:00
init update workarounds for gcc "asm goto" issue 2024-02-23 09:24:47 +01:00
io_uring io_uring/net: fix overflow check in io_recvmsg_mshot_prep() 2024-03-26 18:19:18 -04:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel bpf: Mark bpf_spin_{lock,unlock}() helpers with notrace correctly 2024-03-26 18:19:29 -04:00
lib net: blackhole_dev: fix build warning for ethh set but not used 2024-03-26 18:19:26 -04:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm readahead: avoid multiple marked readahead pages 2024-03-15 10:48:21 -04:00
net ipv6: mcast: remove one synchronize_net() barrier in ipv6_mc_down() 2024-03-26 18:19:28 -04:00
rust rust: upgrade to Rust 1.73.0 2024-02-16 19:10:43 +01:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:24:47 +01:00
scripts gen_compile_commands: fix invalid escape sequence warning 2024-03-26 18:19:11 -04:00
security landlock: Fix asymmetric private inodes referring 2024-03-06 14:48:39 +00:00
sound ASoC: wm8962: Fix up incorrect error message in wm8962_set_fll 2024-03-26 18:19:15 -04:00
tools selftests: forwarding: Add missing multicast routing config entries 2024-03-26 18:19:28 -04:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add Catherine as xfs maintainer for 6.6.y 2024-02-16 19:10:43 +01:00
Makefile Linux 6.6.22 2024-03-15 14:25:07 -04:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.